Terrible Future

Main character Ikki Minakata is a student who aims to become a civil servant to have a stable life. On the summer vacations he is suddenly attacked by a girl who comes from the future to kill him and prevent inventing of the device that put the world to chaos. However, Ikki is protected by an android girl Michelette who also comes from the future to defend Ikki and the future regime.
Protagonist ignores the girls fighting and goes home only to find both girls from future come to his apartment several days later having exhausted their fighting capabilities...

[From vndbreview]